Base station apparatus, communication method, terminal apparatus and integrated circuit

ABSTRACT

Provided are a radio terminal device, a radio base station device, and a channel signal forming method which can prevent quality degradation of the downlink source allocation information by reducing the frequency of the zero information addition process to the downlink resource allocation information when executing communication using an uplink unit band and a plurality of downlink unit bands correlated to the uplink unit band. A base station can execute communication using the uplink unit band and a plurality of downlink unit bands correlated to the uplink unit band. The base station includes: a PDCCH generation unit which includes the uplink allocation information relating to the uplink unit band only in some of the channel signals formed for each of the downlink unit bands; and a padding unit which adds zero information to the downlink allocation information only in the selected some channel signals having the bandwidth of the corresponding downlink unit band smaller than that of the uplink unit band until the downlink allocation information size becomes equal to the uplink allocation information size.

TECHNICAL FIELD

The present invention relates to a radio terminal apparatus, a radiobase station apparatus and a channel signal forming method.

DESCRIPTION OF THE RELATED ART

With 3GPP LTE, OFDMA (Orthogonal Frequency Division Multiple Access) isadopted as a downlink communication scheme. In a radio communicationsystem supporting 3GPP LTE, a base station transmits synchronizingsignals (synchronization channels: SCHs) and broadcast signals(broadcast channels: BCHs) using predetermined communication resources.Then, a terminal first captures an SCH to secure synchronization withthe base station. Then, the terminal acquires parameters (e.g., afrequency bandwidth and so forth) unique to the base station by readingBCH information (see Non-Patent Literatures 1 and 2).

After completing acquisition of the parameters unique to the basestation, the terminal requests the base station for a connection toestablish communication with the base station. The base stationtransmits control information to the terminal having establishedcommunication with the base station using PDCCHs (physical downlinkcontrol channels) if necessary.

Then, the terminal performs “blind detection” on a received PDCCHsignal. That is, a PDCCH signal contains a CRC part, and, in the basestation, this CRC part is masked with the terminal ID of the terminal towhich the PDCCH signal should be transmitted. Therefore, the terminalcannot determine whether or not the PDCCH signal is directed to theterminal until demasking the CRC part of the received PDCCH signal withthe terminal's ID. With this blind detection, when CRC calculation is OKas the result of demasking, this PDCCH signal is determined as a signaldirected to the terminal.

In addition, control information transmitted from a base stationincludes resource allocation information containing information aboutresources allocated from the base station to a terminal. A terminalneeds to receive both downlink resource allocation information anduplink resource allocation information. These downlink resourceallocation information and uplink resource allocation information aretransmitted using PDCCH signals having the same size. A PDCCH signalcontains the type information (e.g., one bit flag) about resourceallocation information. Therefore, even if a PDCCH signal containingdownlink resource allocation information and a PDCCH signal containinguplink resource allocation information have the same size, a terminalcan distinguish between downlink resource allocation information anduplink resource allocation information by checking the type informationabout resource allocation information. Here, the format of PDCCHs usedto transmit uplink resource allocation information is “PDCCH Format 0”,and the format of PDCCHs used to transmit downlink resource allocationinformation is “PDCCH Format 1A.”

However, a case is possible where the uplink bandwidth and the downlinkbandwidth differ, and in this case, the size of information (that is,the number of bits required for transmission) is different betweendownlink resource allocation information and uplink resource allocationinformation. To be more specific, when the uplink bandwidth is small,the size of uplink resource allocation information is small, and, whenthe downlink bandwidth is small, the size of downlink resourceallocation information is small. In this way, when the size ofinformation varies due to a difference in bandwidth, zero information isadded (that is, zero padding is performed) to either resource allocationinformation having a smaller size to make downlink resource allocationinformation and uplink resource allocation information have the samesize. By this means, it is possible to keep the size of PDCCH signalsthe same regardless whether the information is downlink resourceallocation information or uplink resource allocation information.

In addition, standardization of 3GPP LTE-Advanced that realizescommunication faster than 3GPP LTE has been started. A 3GPP LTE-Advancedsystem (hereinafter, also referred to as “LTE-A system”) follows a 3GPPLTE system (hereinafter, also referred to as “LTE system”). With 3GPPLTE-Advanced, base stations and terminals that can perform communicationin a wideband frequency equal to or higher than 20 MHz, will beintroduced in order to realize a downlink transmission speed equal to orhigher than maximum 1 Gbps.

Moreover, with 3GPP LTE-Advanced, a case is possible where thecommunication bandwidth of the uplink is not symmetrical to thecommunication bandwidth of the downlink, taking into account that thereis a difference in the required throughput between the uplink and thedownlink. To be more specific, with 3GPP LTE-Advanced, the communicationbandwidth of the downlink may be wider than the communication bandwidthof the uplink.

Here, a base station supporting an LTE-A system (hereinafter, “LTE-Abase station”) is configured to be able to perform communication using aplurality of “component bands.” “Component band” is a band having awidth of the maximum 20 MHz, and is defined as the basic unit ofcommunication bands. In addition, “component band” in the downlink(hereinafter referred to as “downlink component band”) may be defined asa band separated according to downlink frequency band informationcontained in a BCH broadcasted from a base station, or a band defined bythe distribution width in which downlink control channels (PDCCHs) aredistributed and assigned in the frequency domain. On the other hand,“component band” in the uplink (hereinafter “uplink component band”) maybe defined as a band separated according to uplink frequency bandinformation contained in a BCH broadcasted from a base station, or thebasic unit of communication bands equal to or lower than 20 MHzincluding a PUSCH (physical uplink shared channel) around the center andincluding PUCCHs in both end parts. Here, in 3GPP LTE-Advanced,“component band(s)” may be written as “component carrier(s)” in English.

FIG. 1 shows an arrangement example of channels in an LTE-A system wherethe communication bandwidth (the number of component bands) for theuplink is not symmetrical to the communication bandwidth for thedownlink. In FIG. 1, in order to make a terminal transmit an uplinksignal, an LTE-A base station reports resource allocation informationfrom both two downlink component bands, using PDCCHs. The uplinkcomponent band is associated with both downlink component bands, andtherefore a PUSCH is transmitted using the same uplink component bandeven if uplink resource allocation information is transmitted usingeither downlink component band. In addition, downlink resourceallocation information may be transmitted from both of two downlinkcomponent bands, and each downlink resource allocation information isused to indicate, to a terminal, a downlink-allocated resource in thedownlink component band from which the resource allocation informationis transmitted.

An LTE-A terminal can receive a plurality of component bands byreceiving resource allocation information in this way. Here, an LTEterminal can receive only one component band at a time in this way,bundling a plurality of component bands into an allocated band for asingle communication is referred to as “carrier aggregation.” It ispossible to improve throughput using this carrier aggregation.

CITATION LIST Non-Patent Literature

-   NPL 1-   3GPP TS 36.211 V8.3.0, “Physical Channels and Modulation (Release    8),” May 2008-   NPL 2-   3GPP TS 36.212 V8.3.0, “Multiplexing and channel coding (Release    8),” May 2008-   NPL 3-   3GPP TS 36.213 V8.3.0, “Physical layer procedures (Release 8),” May    2008

BRIEF SUMMARY Technical Problem

Here, in FIG. 1, the downlink communication bandwidth of an LTE-A systemshown is 30 MHz, and includes two component bands including a downlinkcomponent band of 20 MHz in the low frequency side and a downlinkcomponent band of 10 MHz in the high frequency side. On the other hand,the uplink communication bandwidth is 20 MHz and includes one uplinkcomponent band.

In FIG. 1, the downlink component band in the low frequency side and theuplink component band have the same bandwidth, and therefore, withrespect to this pair, uplink resource allocation information anddownlink resource allocation information have the same size. Therefore,zero padding is not performed. By contrast with this, the downlinkcomponent band in the high frequency side and the uplink component bandhave different bandwidths, and therefore, with respect to this pair,zero information is added to the downlink resource allocationinformation having a smaller size until this downlink resourceallocation information and the uplink resource allocation informationhave the same size. However, zero padding is performed for sizeadjustment, and zero information itself carries no meaning That is,signals, which are actually unnecessary, are included in downlinkcontrol information, and therefore, when the power for the whole systemis fixed, the power per information bit, which is actually necessary,decreases.

In addition, generally, the degree of importance of downlink controlinformation is higher than that of uplink control information. It isbecause that downlink control information is used to report not onlyresource allocation information about downlink data channels, but alsoscheduling information about other important information (e.g., paginginformation and broadcast information). Therefore, it is desired todecrease the frequency of performing zero padding on downlinkinformation.

Here, frequency diversity effect obtained using PDCCHs depends on thebandwidth of a downlink component band. Accordingly, the frequencydiversity effect is small in a downlink component band having a narrowbandwidth, and therefore, it is desired to remove factors for qualitydeterioration as much as possible. However, when a downlink componentband has a narrower bandwidth, the downlink component band is highlylikely to be subject to zero padding.

This situation has not been impossible in an LTE system in which thereis not concept of carrier aggregation, because the downlink frequencyband is generally greater than the uplink frequency band in an LTEsystem. By contrast with this, in an LTE-A system in which carrieraggregation is introduced and a plurality of downlink component bandsare associated with one uplink component band, even if the entiredownlink frequency bandwidth is greater than the uplink frequencybandwidth, when each component band is focused on, a case is likely tofrequently occur where a downlink component band is narrower than theuplink component band.

Moreover, in order to prevent zero padding, a case is possible where thesize differs between uplink control information and downlink controlinformation. However, in this case, the terminal side needs to performblind detection separately on two pieces of control information havingdifferent numbers of information bits. Therefore, there is a problem ofincrease in the number of times of blind detections, and therefore thecircuit scale increases.

It is therefore an object of the present invention to provide a radioterminal apparatus, a radio base station apparatus and a channel signalforming method that can prevent deterioration in the quality of downlinkresource allocation information, by reducing the frequency of processingincluding adding zero information to downlink resource allocationinformation when performing communication using an uplink component bandand a plurality of downlink component bands associated with the uplinkcomponent band.

Solution to Problem

The radio terminal apparatus according the present invention that canperform communication using an uplink component band and a plurality ofdownlink component bands associated with the uplink component bandadopts a configuration to include: a radio receiving section thatreceives a control signal containing allocation information per downlinkcomponent band; and a control signal reception processing section thatdetermines a basic information size used in reception processing on acontrol signal in each downlink component band and performs receptionprocessing on the control signal based on the basic information size,wherein in a downlink component band containing uplink resourceallocation information and downlink resource allocation information, thedownlink component band being part of the plurality of downlinkcomponent bands, when an information size determined based on abandwidth of a corresponding downlink component band is greater than aninformation size determined based on a bandwidth of the uplink componentband, the basic information size is an information size determined basedon the bandwidth of the downlink component band; when the informationsize determined based on the bandwidth of the corresponding downlinkcomponent band is smaller than the information size determined based onthe bandwidth of the uplink component band, the basic information sizeis an information size determined based on the bandwidth of the uplinkcomponent band; and with respect to other downlink component bands, thebasic information size is an information size determined based on thebandwidth of the downlink component band regardless of the bandwidth ofthe uplink component band.

The base station according to the present invention that can performcommunication using an uplink component band and a plurality of downlinkcomponent bands associated with the uplink component band adopts aconfiguration to include: a forming section that forms a channel signalper downlink band; and a padding section that adds zero information toeither downlink resource allocation information or uplink resourceallocation information having a smaller size, in a channel signalcontaining both the downlink resource allocation information and theuplink resource allocation information until the downlink resourceallocation information and the uplink resource allocation informationhave a same size, wherein the forming section includes both the uplinkresource allocation information and the downlink resource allocationinformation in only part of the plurality of channel signals formed, andincludes only the downlink resource allocation information in channelsignals other than the part of the plurality of channel signals.

The channel signal forming method according to the present inventionthat forms channel signals containing downlink resource allocationinformation in an uplink component band and a plurality of downlinkcomponent band associated with the uplink component band, respectively,includes: putting uplink resource allocation information about theuplink component band in only part of the channel signals; and addingzero information to either downlink resource allocation information oruplink resource allocation information having a smaller size in achannel signal containing both the downlink resource allocationinformation and the uplink resource allocation information until thedownlink resource allocation information and the uplink resourceallocation information have a same size.

Advantageous Effects of Invention

According to the present invention, when communication is performedusing an uplink component band and a plurality of downlink componentbands associated with the uplink component band, the frequency ofprocessing including adding zero information to downlink resourceallocation information is reduced, and therefore, it is possible toprovide a radio terminal apparatus, a radio base station apparatus and achannel signal forming method that can prevent deterioration in thequality of downlink resource allocation information.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows an arrangement example of channels in an LTE-A system inwhich the communication bandwidth (the number of component bands) of theuplink is not symmetrical to that of the downlink;

FIG. 2 is a block diagram showing a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 3 is a block diagram showing a configuration of a terminalaccording to Embodiment 1 of the present invention;

FIG. 4 explains operation of a base station and operation of terminal;

FIG. 5 is a block diagram showing a configuration of a base stationaccording to Embodiment 3 of the present invention;

FIG. 6 is a block diagram showing a configuration of a terminalaccording to Embodiment 3 of the present invention;

FIG. 7 shows a sequence when a base station and a terminal start carrieraggregation communication;

FIG. 8 is a conceptual diagram showing operation in a newly addeddownlink component band;

FIG. 9 is a conceptual diagram showing operation in the basic componentband set according to a command from a base station; and

FIG. 10 shows an arrangement example of channels in an LTE-A system inwhich the communication bandwidth (the number of component bands) of theuplink is not symmetrical to that of the downlink.

DETAILED DESCRIPTION

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. Here, the same componentsbetween embodiments are assigned the same reference numerals andoverlapping descriptions will be omitted.

Embodiment 1

FIG. 2 is a block diagram showing the configuration of base station 100according to Embodiment 1 of the present invention. In FIG. 2, basestation 100 has control section 101, PDCCH generating section 102,padding section 103, modulation sections 104 and 105, SCH/BCH generatingsection 106, multiplexing section 107, IFFT section 108, CP (cyclicprefix) adding section 109, RF transmission section 110, RF receivingsection 111, CP removing section 112, FFT section 113, extractingsection 114, IDFT section 115 and data receiving section 116. Basestation 100 is configured to be able to perform communication using anuplink component band and a plurality of downlink component bandsassociated with the uplink component band.

Control section 101 generates uplink resource allocation information anddownlink resource allocation information for terminal 200 describedlater, outputs uplink resource allocation information to PDCCHgenerating section 102 and extracting section 114 and outputs downlinkresource allocation information to PDCCH generating section 102 andmultiplexing section 107.

Control section 101 allocates downlink resource allocation informationto all of a plurality of downlink component bands, and allocates uplinkresource allocation information to only part of the plurality ofdownlink component bands. Here, among a plurality of downlink componentbands associated with one uplink component band, uplink resourceallocation information is allocated to, particularly, the downlinkcomponent band having the bandwidth which is the most similar to thebandwidth of the uplink component band. Hereinafter, a target downlinkcomponent band to which uplink resource allocation information isallocated, may also be referred to as “basic component band.”

Control section 101 outputs uplink resource allocation information anddownlink resource allocation information to PDCCH generating section102, and also outputs information about a basic component band(hereinafter may also be referred to as “basic component bandinformation”) to PDCCH generating section 102. Here, SCH/BCH generatingsection 106 may include this basic component band information in a BCH.

In addition, control section 101 delivers bandwidth comparisoninformation indicating size comparison between the bandwidth of a basiccomponent band and the bandwidth of an uplink component band, to paddingsection 103 via PDCCH generating section 102.

PDCCH generating section 102 generates a PDCCH signal to be transmittedin each downlink component band. In this case, PDCCH generating section102 includes uplink resource allocation information and downlinkresource allocation information in the PDCCH signal assigned to thedownlink component band indicated by basic component band information,and includes only downlink resource allocation information in the PDCCHsignal assigned to the other downlink component band. After that, thePDCCH signals are outputted to padding section 103.

Padding section 103 adds zero information to either downlink resourceallocation information or uplink resource allocation information havingthe smaller size until the downlink resource allocation information andthe uplink resource allocation information have the same size in theinputted PDCCH signals. To which of downlink resource allocationinformation or uplink resource allocation information is added zeroinformation, is determined based on bandwidth comparison information.

In addition, padding section 103 adds CRC bits to a PDCCH signal afterpadding processing and masks the CRC bits with the terminal ID. Then,padding section 103 outputs a PDCCH signal after masking, to modulationsection 104.

Modulation section 104 modulates the PDCCH signal inputted from PDCCHgenerating section 102, and outputs a PDCCH signal after modulation tomultiplexing section 107.

Modulation section 105 modulates inputted transmission data (downlinkdata) and outputs a transmission data signal after modulation tomultiplexing section 107.

SCH/BCH section 106 generates an SCH and a BCH, and outputs thegenerated SCH and BCH to multiplexing section 107.

Multiplexing section 107 multiplexes the PDCCH signal inputted frommodulation section 104, the data signal (i.e., PDSCH signal) inputtedfrom modulation section 105, and the SCH and BCH inputted from SCH/BCHgenerating section 106. Here, multiplexing section 107 maps a datasignal (PDSCH signal) to downlink component bands, based on downlinkresource allocation information inputted from control section 101.

IFFT section 108 transforms a multiplexed signal to time waveform, andCP adding section 109 adds a CP to this time waveform to generate anOFDM signal.

RF transmission section 110 applies transmission radio processing(up-conversion, digital-to-analog (D/A) conversion and so forth) to theOFDM signal inputted from CP adding section 109, and transmits theresult via an antenna. By this means, an OFDM signal containing resourceallocation information is transmitted.

RF receiving section 111 applies reception radio processing(down-conversion, analog-to-digital (A/D) conversion and so forth), to areceived radio signal received in a receiving band via an antenna, andoutputs a resultant received signal to CP removing section 112.

CP removing section 112 removes the CP from the received signal, and FFTsection 113 transforms a received signal without a CP to a frequencydomain signal.

Extracting section 114 extracts uplink data from the frequency domainsignal inputted from FFT section 113, based on uplink resourceallocation information inputted from control section 101. IDFT (inversediscrete Fourier transform) section 115 transforms an extracted signalto a time domain signal and outputs the time domain signal to datareceiving section 116.

Data receiving section 116 decodes the time domain signal inputted fromIDFT section 115. Then, data receiving section 116 outputs uplink dataafter decoding as received data.

FIG. 3 is a block diagram showing the configuration of terminal 200according to Embodiment 1 of the present invention. In FIG. 3, terminal200 has RF receiving section 201, CP removing section 202, FFT section203, frame synchronization section 204, demultiplexing section 205,broadcast signal receiving section 206, PDCCH receiving section 207,format determination section 208, PDSCH receiving section 209,modulation section 210, DFT section 211, frequency mapping section 212,IFFT section 213, CP adding section 214 and RF transmission section 215.

RF receiving section 201 applies reception radio processing(down-conversion, analog-to-digital (A/D) conversion and so forth) to areceived radio signal (here, OFDM signal) received in a receiving bandvia an antenna, and outputs a resultant received signal to CP removingsection 202.

CP removing section 202 removes the CP from the received signal, and FFT(fast Fourier transform) section 203 transforms a received signalwithout a CP to a frequency domain signal. This frequency domain signalis outputted to frame synchronization section 204.

Frame synchronization section 204 searches for an SCH contained in thesignal inputted from FFT section 203 and synchronizes with base station100 (frame synchronization). In addition, frame synchronization section204 obtains the cell ID associated with an SCH sequence. That is, framesynchronization section 204 performs the same processing as usual cellsearch. Then, frame synchronization section 204 outputs framesynchronization timing information indicating the frame synchronizationtiming and the signal inputted from FFT section 203, to demultiplexingsection 205.

Demultiplexing section 205 demultiplexes the signal inputted from framesynchronization section 204 into a broadcast signal (i.e., BCH), acontrol signal (i.e., PDCCH signal) and a data signal (i.e., PDSCHsignal), based on the frame synchronization timing information inputtedfrom frame synchronization section 204. Demultiplexing section 205receives information about downlink component bands from broadcastsignal receiving section 206, and extracts a PDCCH signal for each ofdownlink component bands, based on this information.

Broadcast signal receiving section 206 reads the content of the BCHinputted from demultiplexing section 205, and obtains information aboutthe band (uplink and downlink bands) configuration of base station 100,Broadcast signal receiving section 206 obtains, for example, the numberof uplink component bands, the number of downlink component bands, theidentification number and bandwidth of each component band, informationabout association between uplink and downlink component bands, basiccomponent band information and so forth. Here, although it is possibleto calculate a basic component band from the bandwidth of an uplinkcomponent band and the bandwidth of a downlink component band, basestation 100 includes identification information about a basic componentband in a BCH. Broadcast signal receiving section 206 outputs theobtained BCH information to format determination section 208 and PDCCHreceiving section 207.

PDCCH receiving section 207 performs blind detection on a PDCCH signalin each downlink component band, using the size of resource allocationinformation corresponding to the bandwidth of each downlink componentband, the size of resource allocation information corresponding to thebandwidth of the uplink component band, and the terminal ID of terminal200.

That is, PDCCH receiving section 207 first determines a basicinformation size used to process each PDCCH signal, and specifies a partcorresponding to CRC bits contained in each PDCCH signal, according tothe determined basic information size. At this time, in base station100, the size of information may be adjusted using zero padding, asdescribed above. Therefore, PDCCH receiving section 207 specifies a partcorresponding to CRC bits in a PDCCH signal in a basic component band,using the size of basic information (payload size) determined based oneither the bandwidth of the basic component band or the bandwidth of theuplink component band corresponding to the basic component band,whichever is wider. On the other hand, the downlink component band otherthan the basic component band includes only downlink resource allocationinformation. Therefore, PDCCH receiving section 207 specifies a partcorresponding to CRC bits in the downlink component band other than thebasic component band, using the basic information size matching thebandwidth of the downlink component band.

Next, PDCCH receiving section 207 demasks the specified partcorresponding to CRC bits with the terminal ID of terminal 200, and, ifthe result of CRC calculation for the entire PDCCH signal is OK,determines that this PDCCH signal is directed to terminal 200. In thisway, the PDCCH signal determined as a signal directed to terminal 200 isoutputted to format determination section 208.

Format determination section 208 determines whether the format of thePDCCH signal received from PDCCH receiving section 207, is Format 0 orFormat 1A, based on the type information about the resource allocationinformation included in this PDCCH signal. When determining that theformat is Format 0, format determination section 208 outputs the uplinkresource allocation information contained in the PDCCH signal tofrequency mapping section 212. In addition, when determining that theformat is Format 1A, format determination section 208 outputs thedownlink resource allocation information contained in the PDCCH signalto PDSCH receiving section 209.

PDSCH receiving section 209 extracts received data from the PDSCH signalinputted from demultiplexing section 205, based on the downlink resourceallocation information inputted from format determination section 208.

Modulation section 210 modulates transmission data, and outputs aresultant modulated signal to DFT (discrete Fourier transform) section211.

DFT section 211 transforms the modulated signal inputted from modulationsection 210, and outputs a plurality of resultant frequency componentsto mapping section 212.

Frequency mapping section 212 maps the plurality of frequency componentsinputted from DFT section 211 to a PUSCH assigned to the uplinkcomponent band.

IFFT section 213 transforms the plurality of mapped frequency componentsto a time domain waveform, and CP adding section 214 adds a CP to thetime domain waveform.

RF transmission section 215 applies transmission radio processing(up-conversion, digital-to-analog (D/A) conversion and so forth) to asignal with the CP, and transmits the result via an antenna.

Next, operation of base station 100 and terminal 200 having theabove-described configurations will be explained. FIG. 4 explainsoperation of base station 100 and terminal 200.

In FIG. 4, one uplink component band UB 1 is associated with threedownlink component bands DBs 1 to 3. Here, size comparison between thebandwidths of respective component bands as follows. Respectivebandwidths of downlink component bands DBs 1 and 3 are wider than thebandwidth of uplink component band UB 1, The bandwidth of downlinkcomponent band DB 2 is narrower than the bandwidth of uplink componentband UB 1. The bandwidth of downlink component band DB 1 is wider thanthe bandwidth of downlink component band DB 3. The bandwidth of downlinkcomponent band DB 1 is similar to the bandwidth of uplink component bandUB 3 more than the downlink component band DB 2. That is, here, downlinkcomponent band DB 3 is the basic component band.

Base station 100 allocates uplink component band UB 1 to terminal 200 asan uplink resource, and allocates downlink component bands DBs 1 to 3 asdownlink resources.

Then, base station 100 includes uplink resource allocation informationand downlink resource allocation information in PDCCH signals andtransmits the result to terminal 200.

Here, base station 100 does not include uplink resource allocationinformation in all PDCCH signals, but includes uplink resourceallocation information in only PDCCH signals assigned to part ofdownlink component bands. On the other hand, downlink resourceallocation information is included in all PDCCH signals.

Particularly, with the present embodiment, the basic component band is adownlink component band having the bandwidth which is the most similarto the bandwidth of the uplink component band. Therefore, in FIG. 4,uplink resource allocation information is transmitted in only downlinkcomponent band DB 3, which is the basic component band. Here, in FIG. 4,arrows from a PDCCH to uplink data (UL data) mean that uplink resourceallocation information is transmitted using the PDCCH. In addition,arrows from each PDCCH to downlink data (DL data) or a D-BCH mean thatdownlink resource allocation information is transmitted using thatPDCCH.

In addition, CRC bits are added to a PDCCH signal in padding section103. These CRC bits have been masked with the terminal ID assigned toterminal 200.

In addition, adjustment of the size of information is performed on PDCCHsignals if necessary. This adjustment of the size of information isperformed on a PDCCH signal containing both uplink resource allocationinformation and downlink resource allocation information (that is, aPDCCH signal in the basic component band) in padding section 103. To bemore specific, padding section 103 adds zero information to eitherdownlink resource allocation information or uplink resource allocationinformation having the smaller size until the downlink resourceallocation information and the uplink resource allocation informationhave the same size. Here, in FIG. 4, the thickness of each arrowrepresents the size of the corresponding resource allocationinformation, where uplink resource allocation information and downlinkresource allocation information have the same size in the basiccomponent band.

Meanwhile, in terminal 200 that receives PDCCH signals, PDCCH receivingsection 207 performs blind detection on PDCCH signals in respectivedownlink component bands, using the size of resource allocationinformation corresponding to the bandwidth of each downlink componentband, the size of resource allocation information corresponding to thebandwidth of the uplink component band and the terminal ID of terminal200.

That is, PDCCH receiving section 207 first determines a basicinformation size used for processing each PDCCH, and specifies a partcorresponding to CRC bits contained in a PDCCH signal according to thedetermined basic information size. To be more specific, in a PDCCHsignal in downlink component band DB 3, which is the basic componentband, a part corresponding to CRC bits specified using a basicinformation size (payload size) is determined based on the wider one ofthe bandwidth of downlink component band DB 3 and the bandwidth ofuplink component band UB 1 corresponding to downlink component band DB 3(that is, the bandwidth of downlink component band DB 3). Meanwhile,PDCCH receiving section 207 specifies a part corresponding to CRC bitsin each of the downlink component bands other than the basic componentband, using the basic information size according to the bandwidth ofeach downlink component band. In this way, blind detection processing isswitched between the basic component band and the downlink componentbands other than the basic component band.

Next, PDCCH receiving section 207 demasks the specified partcorresponding to CRC bits with the terminal ID of terminal 200, and, ifthe result of CRC calculation for the entire PDCCH signal is OK,determines that this PDCCH signal is directed to terminal 200.

Then, format determination section 208 determines whether the format ofthe PDCCH signal received from PDCCH receiving section 207, is Format 0or Format 1A, based on the type information about the resourceallocation information included in this PDCCH signal.

As described above, according to the present embodiment, PDCCH signalscontaining uplink resource allocation information are limited to thePDCCH signal assigned to part of downlink component bands, and thereforeit is possible to reduce the rate of performing zero padding on downlinkresource allocation information having a high degree of importance.Particularly, with the present embodiment, the basic component band is adownlink component band having the bandwidth which is the most similarto the bandwidth of the uplink component band, and therefore it ispossible to limit a downlink component band in which zero padding isperformed on downlink resource allocation information, to at most oneband, that is, the basic component band.

In addition, only downlink resource allocation information is includedin PDCCH signals in the downlink component bands other than the basiccomponent band, so that the above-described adjustment of informationsize is not required. Therefore, it is possible to reduce the rate inwhich zero padding is performed on downlink resource allocationinformation. Likewise, it is possible to minimize the number of times ofpadding and the frequency to perform padding on uplink resourceallocation information.

That is, it is possible to minimize the frequency of performing zeropadding processing on both uplink resource allocation information anddownlink resource allocation information, so that it is possible toimprove the quality of both uplink resource allocation information anddownlink resource allocation information and also improve systemperformance.

Moreover, according to the present embodiment, adjustment of the size ofinformation is performed to make downlink resource allocationinformation and uplink resource allocation information have the samesize in a PDCCH signal in the basic component band.

By this means, it is possible to match the position of a partcorresponding to CRC bits in a PDCCH signal between downlink resourceallocation information and uplink resource allocation information.Therefore, in the receiving side, it is possible to specify a partcorresponding to CRC bits without distinguishing between downlinkresource allocation information and uplink resource allocationinformation, based on the information size (payload size) determinedbased on the wider one of the bandwidth of the basic component band andthe bandwidth of the uplink component band corresponding to the basiccomponent band, or the information size determined based on the widerone of downlink resource allocation information determined by thebandwidth of the basic component band or uplink resource allocationinformation determined by the bandwidth of the uplink component band.That is, it is possible to apply the same blind detection processing todownlink resource allocation information and uplink resource allocationinformation, and therefore it is possible to prevent increase in thenumber of times of blind detections.

Embodiment 2

Even if an uplink component band and a downlink component band have thesame bandwidth, a case is possible in which downlink resource allocationinformation and uplink resource allocation information have differentsizes, and the present embodiment differs from Embodiment 1 only in thatthe case is focused.

That is, with Embodiment 1, a case has been explained in which downlinkresource allocation information and uplink resource allocationinformation in a downlink component band as the basic component band,have the same size as long as an uplink component band and a downlinkcomponent band have the same bandwidth. By contrast with this, with thepresent embodiment, even if an uplink component band and a downlinkcomponent band have the same bandwidth, downlink resource allocationinformation and uplink resource allocation information haveapproximately the same size, but do not have exactly the same size. Itis because, when an uplink component band and a downlink component bandhave the same size, the amount of information required to indicateresource positions is the same, but the amount of information requiredto report information about other controls differs between downlinkresource allocation information and uplink resource allocationinformation. In addition, when a difference in the bandwidth between anuplink component band and a downlink component band is greater, adifference in the size between downlink resource allocation informationand uplink resource allocation information increases.

Therefore, with the present embodiment, in order to make downlinkresource allocation information and uplink resource allocationinformation have the same size, when downlink resource allocationinformation and uplink resource allocation information have differentsizes, zero information is added to resource allocation informationallocated to PDCCHs in part of downlink component bands (zero padding).

Now, the present embodiment will be described in detail. Here, the basicconfigurations of a base station and a terminal according to the presentembodiment are the same as the configurations of a base station and aterminal described in Embodiment 1. Therefore, a base station and aterminal according to the present embodiment will be described withreference to FIG. 2 and FIG. 3.

Control section 101 in base station 100 (FIG. 2) according to thepresent embodiment delivers information size comparison informationindicating size comparison between the size of downlink resourceallocation information determined by the bandwidth of a basic componentband and the size of uplink resource allocation information determinedby the bandwidth of an uplink component band, to padding section 103 viaPDCCH generating section 102.

Padding section 103 adds zero information to either downlink resourceallocation information or uplink resource allocation information havinga smaller size until the downlink resource allocation information anduplink resource allocation information have the same size. To which ofdownlink resource allocation information and uplink resource allocationinformation is added zero information is determined based on informationsize comparison information.

Meanwhile, PDCCH receiving section 207 in terminal 200 (FIG. 3) performsblind detection on a PDCCH signal in each downlink component band, usingthe size of resource allocation information corresponding to thebandwidth of each downlink component band, the size of resourceallocation information corresponding to the bandwidth of an uplinkcomponent band, and the terminal ID of terminal 200.

That is, PDCCH receiving section 207 first determines a basicinformation size used for processing each PDCCH, and specifies a partcorresponding to CRC bits contained in a PDCCH signal according to thedetermined basic information size. At this time, in base station 100,adjustment of the size of information may be performed using zeropadding as described above. Therefore, PDCCH receiving section 207specifies a part corresponding to CRC bits in a PDCCH signal in a basiccomponent band, using the greater one of the size of downlink resourceallocation information determined based on the bandwidth of the basiccomponent band and the size of uplink resource allocation informationdetermined based on the bandwidth of the uplink component bandcorresponding to the basic component band, as a basic information size(payload size). On the other hand, the downlink component bands otherthan the basic component band contain only downlink resource allocationinformation. Therefore, PDCCH receiving section 207 specifies a partcorresponding to CRC bits in each downlink component band other than thebasic component band, using the basic information size determined basedon the bandwidth of the downlink component band.

Next, operation of base station 100 and terminal 200 having the abovedescribed configurations will be described with reference to FIG. 4 likein Embodiment 1.

In FIG. 4, one uplink component band UB 1 is associated with threedownlink component bands DBs 1 to 3 like in Embodiment 1. Here, in FIG.4, size comparison between respective bandwidths of component bands isas follows. Respective bandwidths of downlink component bands DBs 1 and3 are wider than the bandwidth of uplink component band UB 1. Thebandwidth of downlink component band DB 2 is narrower than the bandwidthof uplink component band UB 1. The bandwidth of downlink component bandDB 1 is wider than the bandwidth of downlink component band DB 3. Thebandwidth of uplink component band UB 1 is similar to the bandwidth ofthe bandwidth of downlink component band DB 3 more than the bandwidth ofdownlink component band DB 2. That is, here, downlink component band DB3 is the basic component band.

Base station 100 allocates uplink component band UB 1 to terminal 200 asan uplink resource and allocates downlink component bands DBs 1 to 3 toterminal 200 as downlink resources.

Then, base station 100 includes uplink resource allocation informationand downlink resource allocation information in PDCCH signals andtransmits these signals to terminal 200.

Here, base station 100 does not include uplink resource allocationinformation in all PDCCH signals, but includes uplink resourceallocation information in only PDCCH signals assigned to part ofdownlink component bands. On the other hand, downlink resourceallocation information is included in all PDCCH signals.

Particularly, with the present embodiment, the basic component band is adownlink component band having the bandwidth which is the most similarto the bandwidth of the uplink component band. Therefore, in FIG. 4,uplink resource allocation information is transmitted in only downlinkcomponent band DB 3, which is the basic component band. Here, in FIG. 4,arrows from a PDCCH to uplink data (UL data) mean that uplink resourceallocation information is transmitted using the PDCCH. In addition,arrows from each PDCCH to downlink data (DL data) or a D-BCH mean thatdownlink resource allocation information is transmitted using the PDCCH.

In addition, CRC bits are added to each PDCCH signal in padding section103. These CRC bits are masked with the terminal ID assigned to terminal200.

In addition, adjustment of the size of information is performed on PDCCHsignals if necessary.

This adjustment of the size of information is performed on a PDCCHsignal containing both uplink resource allocation information anddownlink resource allocation information (that is, a PDCCH signal in thebasic component band) in padding section 103. To be more specific,padding section 103 adds zero information to either downlink resourceallocation information or uplink resource allocation information havinga smaller size until the downlink resource allocation information andthe uplink resource allocation information have the same size. Here, inFIG. 4, the thickness of each arrow represents the size of thecorresponding resource allocation information, where uplink resourceallocation information and downlink resource allocation information havethe same size in the basic component band.

Meanwhile, in terminal 200 that receives PDCCH signals, PDCCH receivingsection 207 performs blind detection on PDCCH signals in respectivedownlink component bands, using the size of resource allocationinformation corresponding to the bandwidth of each downlink componentband, the size of resource allocation information corresponding to thebandwidth of the uplink component band and the terminal ID of terminal200.

That is, PDCCH receiving section 207 first determines a basicinformation size used for processing each PDCCH, and specifies a partcorresponding to CRC bits contained in a PDCCH signal according to thedetermined basic information size. To be more specific, in a PDCCHsignal in downlink component band DB 3, which is the basic componentband, a part corresponding to CRC bits, using the greater one of thesize of downlink resource allocation information determined based on thebandwidth of downlink component band DB 3 and the size of uplinkresource allocation information determined based on the bandwidth ofuplink component band UB 1 corresponding to downlink component band DB3, as a basic information size (payload size). Meanwhile, PDCCHreceiving section 207 specifies a part corresponding to CRC bits in eachof the downlink component bands other than the basic component band,using the basic information size determined based on the bandwidth ofeach downlink component band. In this way, blind detection processing isswitched between the basic component band and the downlink componentbands other than the basic component band.

Next, PDCCH receiving section 207 demasks the specified partcorresponding to CRC bits with the terminal ID of terminal 200, and, ifthe result of CRC calculation for the entire PDCCH signal is OK,determines that this PDCCH signal is directed to terminal 200.

Then, format determination section 208 determines whether the format ofthe PDCCH signal received from PDCCH receiving section 207, is Format 0or Format 1A, based on the type information about the resourceallocation information included in this PDCCH signal.

As described above, according to the present embodiment, PDCCH signalscontaining uplink resource allocation information are limited to thePDCCH signal assigned to part of downlink component bands like inEmbodiment 1, and therefore it is possible to reduce the rate ofperforming zero padding on downlink resource allocation informationhaving a high degree of importance. Particularly, with the presentembodiment, the basic component band is a downlink component band havingthe bandwidth which is the most similar to the bandwidth of the uplinkcomponent band, and therefore it is possible to limit a downlinkcomponent band in which zero padding is performed on downlink resourceallocation information, to at most one band, that is, the basiccomponent band.

In addition, only downlink resource allocation information is includedin PDCCH signals in the downlink component bands other than the basiccomponent band, so that the above-described adjustment of informationsize is not required. Therefore, it is possible to reduce the rate ofperforming zero padding on downlink resource allocation information.Likewise, it is possible to minimize the number of times of performingpadding and the frequency of performing padding on uplink resourceallocation information.

That is, it is possible to minimize the frequency of performing zeropadding processing on both uplink resource allocation information anddownlink resource allocation information, so that it is possible toimprove the quality of both uplink resource allocation information anddownlink resource allocation information and also improve systemperformance.

Embodiment 3

The present embodiment differs from Embodiments 1 and 2 in that a basestation variably sets a base component band for each terminal.

That is, in Embodiment 3, at the time a base station starts high-speedcommunication with a certain terminal using carrier aggregation, thebasic component band is set according to the same criterion as inEmbodiment 1 or 2. However, with Embodiment 3, a base station cancommand terminals to add and change the basic component band at anytime.

Now, each component and the operation in base station 300 and terminal400 according to Embodiment 3 of the present invention will be describedin detail with reference to FIG. 5 to FIG. 9.

FIG. 5 is a block diagram showing the configuration of base station 300according to Embodiment 3 of the present invention. As compared to basestation 100 shown in FIG. 2, base station 300 shown in FIG. 5 hascontrol section 301 instead of control section 101, padding section 302instead of padding section 103 and modulation section 305 Instead ofmodulation section 105. Here, in FIG. 5, the same components as in FIG.2 are assigned the same reference numerals and descriptions will beomitted.

Control section 301 in base station 300 according to the presentembodiment holds basic component band information, which is set by basestation 300, for each terminal 400. Here, a plurality of basic componentbands may be set for one terminal 400.

In addition, control section 301 delivers basic component band settinginformation set for each terminal 400, and “information size comparisoninformation” which represents size comparison between the size ofdownlink resource allocation information determined based on thebandwidth of each basic component band and the size of uplink resourceallocation information determined based on the bandwidth of the uplinkcomponent band, to padding section 303 via PDCCH generating section 102.

Moreover, when changing the basic component band setting information setfor terminal 400, in order to transmit the thing as data for terminal400, control section 301 outputs new “basic component band settinginformation” to modulation section 305.

Padding section 303 adds zero information to either downlink resourceallocation information or uplink resource allocation information havingthe smaller size until the downlink resource allocation information andthe uplink resource allocation information have the same size. To whichof downlink resource allocation information and uplink resourceallocation information is added zero information is determined based oninformation size comparison information. Resource allocation informationto which zero information is added is outputted to modulation section104 if necessary.

When receiving the basic component band setting information for terminal300, modulation section 305 modulates that information as part oftransmission data to terminal 300 and outputs the result to multiplexingsection 107.

FIG. 6 is a block diagram showing the configuration of terminal 400according to Embodiment 3 of the present invention. As compared toterminal 200 according to Embodiment 1 shown in FIG. 3, terminal 400shown in FIG. 6 has PDCCH receiving section 407 instead of PDCCHreceiving section 207 and has PDSCH receiving section 409 instead ofPDSCH receiving section 209. Here, in FIG. 6, the same components as inFIG. 3 are assigned the same reference numerals and descriptions will beomitted.

PDCCH receiving section 407 in terminal 400 according to the presentembodiment performs blind detection on PDCCH signals in respectivedownlink component bands, using the size of resource allocationinformation corresponding to the bandwidth of each downlink componentband, the size of resource allocation information corresponding to thebandwidth of the uplink component band and the terminal ID of terminal400.

That is, PDCCH receiving section 407 first determines a basicinformation size used to process each PDCCH, and specifies a partcorresponding to CRC bits contained in a PDCCH signal according to thedetermined basic information size. At this time, in base station 300,adjustment of the size of information may be performed using zeropadding as described above. Therefore, PDCCH receiving section 407specifies a part corresponding to CRC bits in a PDCCH signal in eachbasic component band, using the greater one of the size of downlinkresource allocation information determined based on the bandwidth ofeach basic component band and the size of uplink resource allocationinformation determined based on the bandwidth of the uplink componentband corresponding to the basic component band, as a basic informationsize (payload size). On the other hand, the downlink component bandsother than the basic component band contain only downlink resourceallocation information. Therefore, PDCCH receiving section 407 specifiesa part corresponding to CRC bits in each downlink component band otherthan the basic component band, using the basic information sizedetermined based on the bandwidth of the downlink component band.

in addition, PDCCH receiving section 407 determines a plurality of basiccomponent bands described above, according to basic component bandsetting information inputted from PDSCH receiving section 409.

PDSCH receiving section 409 extracts received data from a PDSCH signalinputted from demultiplexing section 205, based on downlink resourceallocation information inputted from format determination section 208.Here, when the received data contains information reporting change inthe basic component band setting, PDSCH receiving section 409 outputsthat information to PDCCH receiving section 407 as new basic componentband setting information.

Next, operation of base station 300 and terminal 400 having theabove-described configurations will be described using FIG. 7 to FIG. 9as support.

FIG. 7 shows a sequence when base station 300 and terminal 400 startcarrier aggregation communication. As shown in FIG. 7, base station 300periodically transmits uplink component band information using a certaindownlink component band (downlink component band 1 in FIG. 7) (step 1).When successfully receiving the uplink component band information frombase station 300, terminal 400 requests to start communication with basestation 300 using that uplink component band, and therefore startscommunication with base station 300 (step 2). In this case, only onedownlink component band and one uplink component band are set forterminal 400, and therefore, this downlink component band (downlinkcomponent band 1 in FIG. 7) is set for base station 300 and terminal 400as the basic component band.

After communication between base station 300 and terminal 400 isestablished, when base station 300 sets aggregation communication withterminal 400, depending on the situation of communication traffic, basestation 300 reports that downlink component band 2 is used incommunication with terminal 400, to terminal 400 individually, so thatcarrier aggregation communication is set between base station 300 andterminal 400 (step 3). This individual report (dedicated signaling) toterminal 400 includes, for example, plurality of information elementsincluding the frequency position and frequency bandwidth of a componentband newly added (i.e., downlink component band 2), informationindicating whether or not the component band newly added is set as thebasic component band, and so forth. Here, at this time, only one uplinkcomponent band is set, and therefore two component bands used in carrieraggregation are both associated with that uplink component band.

Next, FIG. 8 is a conceptual diagram showing operation in theabove-described downlink component band newly added. In FIG. 8, thebandwidth of downlink component band 1 originally used in communicationis 15 MHz, and the bandwidth of downlink component band 2 newly added is10 MHz, where both bandwidths are smaller than the bandwidth (20 MHz) ofuplink component band 1.

As shown in FIG. 7, in the initial state in which terminal 400 startscommunication with base station 300 (that is, before carrier aggregationcommunication is set: step 2), only one downlink component band is setfor terminal 400, so that downlink component band 1 is the basiccomponent band for terminal 400 regardless of size comparison with thebandwidth of the uplink component band.

By contrast with this, when carrier aggregation communication is startedbetween base station 300 and terminal 400 (step 3 in FIG. 8), whether ornot a downlink component band newly added is set as the basic componentband is determined based on whether or not information elementscontained in dedicated signaling from base station 300 include basiccomponent band setting information. That is, a flow of adding a downlinkcomponent band is different from a flow of determining an added downlinkcomponent band as the basic component band.

To be more specific, if there is an information element containing basiccomponent band setting information in dedicated signaling transmittedfrom base station 300 to terminal 400 at the time of starting carrieraggregation, a downlink component band newly added is set as the basiccomponent band without any conditions.

On the other hand, if there is no information element containing basicelement band setting information in the above-described dedicatedsignaling, whether or not a downlink component band newly added is thebasic component band is determined in the terminal 400 side, based on“specified default configuration”). That is, in order to determinewhether or not a component band newly added is set as the basiccomponent band, terminal 400 compares between the size of downlinkresource allocation information determined based on the bandwidth of thecomponent band newly added (i.e., downlink component band 2) and thesize of uplink resource allocation information determined based on thebandwidth of uplink component band 1. Then, as the result of thecomparison, when the size of the downlink resource allocationinformation is equal to or greater than the size of the uplink resourceallocation information, terminal 400 sets the downlink component bandnewly added as the basic component band, and, on the other hand, whenthe size of the uplink resource allocation information is greater thanthe size of the downlink resource allocation information, does not setthe downlink component band newly added, as the basic component band. InFIG. 8, the size of the uplink resource allocation information isgreater, and therefore the downlink component band newly added is notset as the basic component band.

That is, base station 300 determines whether or not to transmit Format 0from the newly added downlink band to terminal 400 as default setting,based on the above-described comparison result. In addition, PDCCHreceiving section 407 in terminal 400 determines the size of downlinkresource allocation information, based on the above-described comparisonresult.

Here, even if the basic component band is set in the initial state inwhich carrier aggregation is started between base station 300 andterminal 400 as described above, after that, base station 300 reports aninformation element containing basic component band setting informationto terminal 400 individually, depending on situations, and therefore canchange whether or not downlink component band 2 is the basic componentband for terminal 400. Then, when downlink component band 2 is set asthe basic component band, base station 300 matches the size of Format 1Awith the size of Format 0 in downlink component band 2, by means ofpadding.

Moreover, when receiving a report that downlink component band 2 is thebasic component band, from base station 300, PDCCH receiving section 407in terminal 400 determines the size of downlink resource allocationinformation assume that the size of Format 1A is the same as the size ofFormat 0 in downlink component band 2 by padding.

As described above, according to the present embodiment, default settingof whether or not a downlink component band newly added at the time ofstarting carrier aggregation is set as the basic component band, isspecified based on comparison between the size of downlink resourceallocation information determined based on the bandwidth of the downlinkcomponent band newly added and the size of uplink resource allocationinformation determined based on the bandwidth of the uplink componentband. Accordingly, it is possible to realize preferable operation forthe performance of Format 1A. Moreover, base station 300 optionallychanges setting of the basic component band for each terminal 400,depending on information of communication traffic.

That is, as default operation, only when the information size determinedbased on the bandwidth of a downlink component band newly added at thetime of starting carrier aggregation is equal to or greater than theinformation size determined based on the bandwidth of the uplinkcomponent band associated with that downlink component band, controlsection 301 in base station 300 determines that downlink component bandas the basic component band. In other words, when a communicationcomponent band is added to the initial communication component band,control section 301 sets, as default operation, only a downlinkcomponent band having a size greater than the information sizedetermined based on the bandwidth of the uplink component bandassociated with that downlink component band, as the basic componentband. By this means, it is possible to prevent padding on downlinkresource allocation information in a downlink component band newlyadded, without signaling to the terminal.

Another Embodiment

(1) With Embodiments 1 and 2, downlink component bands satisfying thefollowing conditions may be selected as the basic component band. Thatis, first, a downlink component band having a bandwidth equal to orgreater than the bandwidth of the uplink component band may be selectedas the basic component band. By this means, it is possible to eliminatezero padding due to the size comparison between the bandwidths withrespect to downlink resource allocation information. In addition,secondly, a downlink component band having a bandwidth, which is equalto or more than the bandwidth of the uplink component band and which isthe most similar to the bandwidth of the uplink component band, may beselected as the basic component band. By this means, also it is possibleto eliminate zero padding due to the size comparison between thebandwidths.

(2) In addition, an LTE-A base station needs to support both LTEterminals and LTE-A terminals. As described above, however, an LTEterminal can perform communication in only one component band at a time.When communicating with base station 100, an LTE terminal needs uplinkresource allocation information and downlink resource allocationinformation, naturally. Therefore, an LTE terminal cannot be allocatedto downlink component bands other than the basic component band, towhich only downlink resource allocation information are transmitted, butcan be allocated to only the basic component band. Therefore, when basestation 100 according to Embodiments 1 and 2 is an LTE-A base station,the basic component band may be a band in which an LTE-A terminal and anLTE terminal can exist together.

An SCH and a P-BCH for at least an LTE terminal are transmitted in aband in which an LTE-A terminal and an LTE terminal can exist togetherin an LTE-A system, as shown in FIG. 10. These SCH and P-BCH for an LTEterminal are used by an LTE-A terminal.

Therefore, in an LTE-A system, terminal 200 according to Embodiments 1and 2 can determine whether or not a certain downlink component band isthe basic component band, based on whether or not the downlink componentband can receive an SCH and a P-BCH for an LTE terminal as a criterionfor determination. Based on the result of the determination, terminal200 can switch blind detection processing between the basic componentband and the other downlink component bands as described above.

In addition, in Embodiments 1 and 2, when information about a coexistingband is reported to terminals by broadcast information such as a BCH,the basic component band may be specified based on the information aboutthe coexisting band. Moreover, information about a coexisting band isnot limited to broadcast information, and may be reported to eachterminal using a dedicated channel.

(3) Also, although cases have been described with the above embodimentas examples where the present invention is configured by hardware, thepresent invention can also be realized by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor whereconnections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosures of Japanese Patent Application No. 2008-281388 filed onOct. 31, 2008 and Japanese Patent Application No. 2009-083043 filed onMar. 30, 2009, including the specifications, drawings and abstracts, areincorporated herein by reference in their entirety.

INDUSTRIAL APPLICABILITY

The radio terminal apparatus, the radio base station apparatus and thechannel signal forming method according to the present invention areuseful to prevent deterioration of the quality in downlink resourceallocation information by reducing the frequency of processing includingadding zero information to downlink resource allocation information whenan uplink component band and a plurality of downlink component bandsassociated with the uplink component band.

The invention claimed is:
 1. A base station apparatus comprising: anallocation information generator which, in operation, generates uplinkresource allocation information relating to a resource allocation of anuplink component carrier and generates downlink resource allocationinformation relating to a resource allocation of respective one of aplurality of downlink component carriers including a basic downlinkcomponent carrier; a padding circuitry which, in operation, appendszeros, when a number of uplink information bits necessary to transmitthe uplink resource allocation information is different from a number ofdownlink information bits necessary to transmit basic downlink resourceallocation information on the basic downlink component carrier, to asmaller one of the uplink resource allocation information and the basicdownlink resource allocation information until a payload size of thesmaller one equals a payload size of the other; and a CRC bit adderwhich, in operation, adds Cyclic Redundancy Check (CRC) bits to theuplink resource allocation information and the basic downlink resourceallocation information output from the padding circuitry, wherein thepayload size of the other is used by a terminal apparatus, whichreceives the uplink resource allocation information and the basicdownlink resource allocation information to which the CRC bits areadded, to determine the added CRC bits, and wherein the added CRC bitsare used by the terminal apparatus to verify whether a Physical DownlinkControl Channel (PDCCH) including the uplink resource allocationinformation and the basic downlink resource allocation information isdirected to the terminal apparatus.
 2. The base station apparatusaccording to claim 1, wherein a bandwidth of the basic downlinkcomponent carrier and a bandwidth of the uplink component carrier areset independently of each other.
 3. The base station apparatus accordingto claim 1, wherein the number of downlink information bits isdetermined based on a bandwidth of the basic downlink component carrierand the number of uplink information bits is determined based on abandwidth of the uplink component carrier.
 4. The base station apparatusaccording to claim 1, wherein the payload size of the other equals agreater one of the number of downlink information bits and the number ofuplink information bits.
 5. The base station apparatus according toclaim 1, wherein the plurality of downlink component carriers furtherincludes a newly added component carrier.
 6. The base station apparatusaccording to claim 1, wherein the basic downlink component carrier is adownlink component carrier having a smallest bandwidth among a pluralityof downlink component carriers each having a larger bandwidth than abandwidth of the uplink component carrier.
 7. A communication methodcomprising: generating uplink resource allocation information relatingto a resource allocation of an uplink component carrier and generatingdownlink resource allocation information relating to a resourceallocation of a respective one of a plurality of downlink componentcarrier including a basic downlink component carrier; appending zeros,when a number of uplink information bits necessary to transmit theuplink resource allocation information is different from a number ofdownlink information bits necessary to transmit basic downlink resourceallocation information on the basic downlink component carrier, to asmaller one of the uplink resource allocation information and the basicdownlink resource allocation information until a payload size of thesmaller one equals a payload size of the other; and adding CyclicRedundancy Check (CRC) bits to the uplink resource allocationinformation and the basic downlink resource allocation information,wherein the payload size of the other is used by a terminal apparatus,which receives the uplink resource allocation information and the basicdownlink resource allocation information to which the CRC bits areadded, to determine the added CRC bits, and wherein the added CRC bitsare used by the terminal apparatus to verify whether a Physical DownlinkControl Channel (PDCCH) including the uplink resource allocationinformation and the basic downlink resource allocation information isdirected to the terminal apparatus.
 8. The communication methodaccording to claim 7, wherein a bandwidth of the basic downlinkcomponent carrier and a bandwidth of the uplink component carrier areset independently of each other.
 9. The communication method accordingto claim 7, wherein the number of downlink information bits isdetermined based on a bandwidth of the basic downlink component carrierand the number of uplink information bits is determined based on abandwidth of the uplink component carrier.
 10. The communication methodaccording to claim 7, wherein the payload size of the other equals agreater one of the number of downlink information bits and the number ofuplink information bits.
 11. The communication method according to claim7, wherein the plurality of downlink component carriers further includesa newly added component carrier.
 12. The communication method accordingto claim 7, wherein the basic downlink component carrier is a downlinkcomponent carrier having a smallest bandwidth among a plurality ofdownlink component carriers each having a larger bandwidth than abandwidth of the uplink component carrier.
 13. A base station apparatuscomprising: an allocation information generator which, in operation,generates uplink resource allocation information relating to a resourceallocation of an uplink component carrier and generates downlinkresource allocation information relating to a resource allocation ofrespective one of a plurality of downlink component carriers including abasic downlink component carrier; a padding circuitry which, inoperation, appends zeros, when a number of uplink information bitsnecessary to transmit the uplink resource allocation information isdifferent from a number of downlink information bits necessary totransmit basic downlink resource allocation information on the basicdownlink component carrier, to a smaller one of the uplink resourceallocation information and the basic downlink resource allocationinformation until a payload size of the smaller one equals a payloadsize of the other; and a CRC bit adder which, in operation, adds CyclicRedundancy Check (CRC) bits to the uplink resource allocationinformation and the basic downlink resource allocation informationoutput from the padding circuitry, wherein the payload size of the otheris used by a terminal apparatus, which receives the uplink resourceallocation information and the basic downlink resource allocationinformation to which the CRC bits are added, to determine the added CRCbits, and wherein the uplink resource allocation information and thebasic downlink resource allocation information are transmitted to andutilized by the terminal apparatus to determine uplink and downlinkresource allocation.
 14. The base station apparatus according to claim13, wherein a bandwidth of the basic downlink component carrier and abandwidth of the uplink component carrier are set independently of eachother.
 15. The base station apparatus according to claim 13, wherein thenumber of downlink information bits is determined based on a bandwidthof the basic downlink component carrier and the number of uplinkinformation bits is determined based on a bandwidth of the uplinkcomponent carrier.
 16. The base station apparatus according to claim 13,wherein the payload size of the other equals a greater one of the numberof downlink information bits and the number of uplink information bits.17. The base station apparatus according to claim 13, wherein theplurality of downlink component carriers further includes a newly addedcomponent carrier.
 18. The base station apparatus according to claim 13,wherein the basic downlink component carrier is a downlink componentcarrier having a smallest bandwidth among a plurality of downlinkcomponent carriers each having a larger bandwidth than a bandwidth ofthe uplink component carrier.